1. Field of the Invention
The present invention relates to an apparatus and method for detecting a voice period in a mobile communication system. More particularly, the present invention relates to an apparatus and method for detecting a talk spurts period and a silent period in a Voice over Internet Protocol (VoIP) session.
2. Description of the Related Art
Recently, there is ongoing discussion on implementation of a Voice over Internet Protocol (VoIP) service in a mobile communication system. The VoIP service has a unique characteristic of statistical multiplexing that is based on a small packet size, a link adaptation, and an ON-OFF period. The statistical multiplexing is possible since the VoIP service has a session in which a talk spurts period and a silent period are repeated alternately. The statistical multiplexing can be achieved by allocating or releasing resources according to the talk spurts period and the silent period.
FIG. 1 illustrates a talk spurts period and a silent period in a VoIP session according to the related art.
Referring to FIG. 1, a talk spurts period 100 for generating a voice packet and a silent period 110 for not generating a voice packet are repeated alternately in the VoIP session. More particularly, the voice packet is generated every 20 milliseconds (ms) in the talk spurts period 100, and a Silence InDication (SID) packet for indicating the silence period is generated every 160 ms in the silent period 110. Since the SID packet is smaller in size than the voice packet, a method of detecting the talk spurts period and the silent period by using the sizes of the voice packet and the SID packet has been used in the related art.
A packet of the VoIP service has a relatively large header size in comparison with a payload, and thus a header compression scheme called RObust Header Compression (ROHC) is adopted in a Long Term Evolution (LTE) system for the effective use of bandwidth. The ROHC scheme changes a header compression rate according to call quality, and consequently changes a packet size. Therefore, there is a problem in that an LTE system that employs the ROHC scheme has difficulty in applying the related art method of detecting the talk spurts period and the silent period by using the sizes of the voice packet and the SID packet. In addition, a method of adaptively changing a source codec rate according to system complexity for the effective use of a bandwidth has recently being discussed, and it is expected that this method will result in more significant changes in the packet size.
In general, a resource is allocated in the talk spurts period and the allocated resource is released in the silent period. Therefore, incorrect detection of the talk spurts period and the silent period results in an unnecessary waste of resources or an increase in a packet delay time, thereby deteriorating call quality.
Accordingly, there is a need for a method of correctly detecting the talk spurts period and the silent period even in an environment where a size of the VoIP packet variably changes.